[gentoo-user] SSD partitioning and migration - caveat

[gentoo-user] SSD partitioning and migration - caveat

[luis jure]

from my recent experience, a caveat if you're using GPT to partition your
disk and intend to boot from it: grub won't install on the disk (at least
if you have an old plain BIOS system, i understand this doesn't happen with
UEFI ??? ).

when i tried to run grub2-install i got this error message:

"this GPT partition label contains no BIOS Boot Partition"

so i had to re-partition the disk and create a small partition at the
beginning without file system and with the bios_grub flag activated. 

after that grub installed OK, and i can boot from my GPT partitioned SSD.

i don't know if this can be of use to somebody.

best,


lj

Re: [gentoo-user] SSD partitioning and migration - caveat

[William Kenworthy]

On 20/07/13 07:44, luis jure wrote:
> 
> 
> from my recent experience, a caveat if you're using GPT to partition your
> disk and intend to boot from it: grub won't install on the disk (at least
> if you have an old plain BIOS system, i understand this doesn't happen with
> UEFI ??? ).
> 
> when i tried to run grub2-install i got this error message:
> 
> "this GPT partition label contains no BIOS Boot Partition"
> 
> so i had to re-partition the disk and create a small partition at the
> beginning without file system and with the bios_grub flag activated. 
> 
> after that grub installed OK, and i can boot from my GPT partitioned SSD.
> 
> i don't know if this can be of use to somebody.
> 
> best,
> 
> 
> lj
> 

You have to map the drive so grub can find it:

olympus ~ # cat /boot/grub/device.map
(hd0)   /dev/sda
olympus

Also, you can put the boot MBR on any disk - even an old spinner and
still have root on the ssd (as above, my ssd is actually /dev/sdd), but
the motherboard cant find any (non-usb) boot device unless I create a
device.map) - once grub is installed its fine and I think I could delete it.

BillK

Re: [gentoo-user] SSD partitioning and migration - caveat

[luis jure]

on 2013-07-20 at 09:51 William Kenworthy wrote:

> You have to map the drive so grub can find it:

no, i don't think that's the problem.

the problem is that with GPT disks you need a BIOS Boot Partition since
they don't have a MBR. is that correct?

https://wiki.archlinux.org/index.php/GRUB#Install_to_GPT_BIOS_boot_partition
http://www.anchor.com.au/blog/2012/10/the-difference-between-booting-mbr-and-gpt-with-grub/

Re: [gentoo-user] SSD partitioning and migration - caveat

[Thomas Mueller]

from luis jure <ljc@internet.com.uy>:

> on 2013-07-20 at 09:51 William Kenworthy wrote:
        
> You have to map the drive so grub can find it:
        
> no, i don't think that's the problem.
        
> the problem is that with GPT disks you need a BIOS Boot Partition since
> they don't have a MBR. is that correct?
 
> https://wiki.archlinux.org/index.php/GRUB#Install_to_GPT_BIOS_boot_partition
> http://www.anchor.com.au/blog/2012/10/the-difference-between-booting-mbr-and-gpt-with-grub/

I think to boot directly from a hard drive, you would need a BIOS Boot Partition or EFI System Partition, depending on whether the motherboard has legacy BIOS or UEFI.  I still boot from a USB stick or System Rescue CD with Syslinux or isolinux and the GRUB2 giant-floppy image (not intended to be written to any actual floppy disk).

I have also made FreeBSD and NetBSD installations on GPT-partitioned USB sticks without any GRUB, using a boot partition (FreeBSD) or installboot in the root partition (NetBSD), not sure how to do this with Linux.  But this only works when one OS is installed on the drive, quite OK for a USB stick in most cases.
        

Tom

Re: [gentoo-user] SSD partitioning and migration - caveat

[Michael Hampicke]

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Am 20.07.2013 05:32, schrieb luis jure:
> on 2013-07-20 at 09:51 William Kenworthy wrote:
> 
>> You have to map the drive so grub can find it:
> 
> no, i don't think that's the problem.
> 
> the problem is that with GPT disks you need a BIOS Boot Partition since
> they don't have a MBR. is that correct?
> 
> https://wiki.archlinux.org/index.php/GRUB#Install_to_GPT_BIOS_boot_partition
> http://www.anchor.com.au/blog/2012/10/the-difference-between-booting-mbr-and-gpt-with-grub/
> 

Correct :-) If I remember correctly, stage2 of the grub bootloader will
be put there.


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